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Hardware Multiplier

  • Thread starter Rich, Under the Affluence
  • Start date
R

Rich, Under the Affluence

Jan 1, 1970
0
4 x 4 hardware multipllier!

OK, it ain't much, and I have no idea if it will work, except watching
the bits all follow their little truth tables in my mental simulator ...
I drew this in Xiilinx, but have no idea yet how to run a simulation,
or dump it to the bitstream that could program the chip (BTW, did I
say that a prospective client has sent me a "CPLD 95XL DEMO BOARD"?
He sent it to me in case I got this one gig, which I think that by
chatting him up on the telephone, I inspired him to find a better,
cheaper faster way, and so talked myself out of a job, but as a sort
of gratituity, I think he's going to let me keep the board. And the
Software. :)

Anyway, there was talk of a hardware multiplier, and I've wanted to
do this since I grasped the concept of "barrel shifter", so I've
drawn a schematic - the Xilinx S/W doesn't have an obvious "save
as", so I screencapped it in PSP. The little labels on the inputs
to the AND gates are 'multiplier(3:0)', expanded, as are the
inputs across the top. The multiplier comes in on the left, and
the product comes out the bottoj.

http://www.abiengr.com/~sysop/images/mult-4x4-sch.gif

Anybody up to callng my bluff? ;-P ;-P ;-P

Cheers!
Rich
 
M

Mac

Jan 1, 1970
0
4 x 4 hardware multipllier!

OK, it ain't much, and I have no idea if it will work, except watching
the bits all follow their little truth tables in my mental simulator ...
I drew this in Xiilinx, but have no idea yet how to run a simulation,
or dump it to the bitstream that could program the chip (BTW, did I
say that a prospective client has sent me a "CPLD 95XL DEMO BOARD"?
He sent it to me in case I got this one gig, which I think that by
chatting him up on the telephone, I inspired him to find a better,
cheaper faster way, and so talked myself out of a job, but as a sort
of gratituity, I think he's going to let me keep the board. And the
Software. :)

Anyway, there was talk of a hardware multiplier, and I've wanted to
do this since I grasped the concept of "barrel shifter", so I've
drawn a schematic - the Xilinx S/W doesn't have an obvious "save
as", so I screencapped it in PSP. The little labels on the inputs
to the AND gates are 'multiplier(3:0)', expanded, as are the
inputs across the top. The multiplier comes in on the left, and
the product comes out the bottoj.

http://www.abiengr.com/~sysop/images/mult-4x4-sch.gif

Anybody up to callng my bluff? ;-P ;-P ;-P

Cheers!
Rich

Your gif was almost illegible.

You know, you can just imply a hardware multiplier in verilog or
VHDL, and I'm pretty sure the tool will make the inference for you.

If you want me to test your multiplier, can you put up the design
files?

There is a free version of the Xilinx software (webpack), by the way,
which will easily handle small designs like this. And there is a free
simulator, too, which you download separately. It's Modelsim, XE (xilinx
edition).

In fact, you could do a fair amount of design work with nothing more than
this.

--Mac
 
R

Rich Grise

Jan 1, 1970
0
Your gif was almost illegible.

Sorry for that. You shouldn't really need to read the lables to
see that it's and gates and 1-bit adders, but the top four lines
are multiplicand(3:0), the four down the left are multiplier(4:0),
with multiplier(0) on top, and the 8 outputs at the bottom are
product(7:0). The labels on teh intermediate and inputs are just
multiplier(3:0), because I didn't want to squeeze in wires - they
just stairstep their way down.
You know, you can just imply a hardware multiplier in verilog or
VHDL, and I'm pretty sure the tool will make the inference for you.

Oh, yeah, but that's not what I wanted to do. I wanted to see if I
could slap one together with adders and gates. :)
If you want me to test your multiplier, can you put up the design
files?

Well, I can, but I'm not very proud of them - I should have had the
tutorial open on the side, because there's some stuff I've left out
and some stuff I have yet to do. I was kind of jazzed at getting
the schematic this far, because building a hardware multiplier (or
even just drawing one) has been a dream since I heard of such a
thing. :)
There is a free version of the Xilinx software (webpack), by the way,
which will easily handle small designs like this. And there is a free
simulator, too, which you download separately. It's Modelsim, XE (xilinx
edition).

Yeah, that's exactly what I'm using, in schematic entry mode. Like I said,
I still have some RTFM to do to get into any more depth.
In fact, you could do a fair amount of design work with nothing more
than this.

Exactly - and the thing that prompted it is that this client sent
me a little "Demo Board" about 2 1/2" x 4 1/2" with an XC9572 on
it and 64 I/O header pins. :)
http://www.abiengr.com/~sysop/images/CPLD_95XL_DEMO_BOARD.jpg

So, when I get a round tuit, I'll not only simulate this thing,
but bring the inputs out to pins, and use the LEDS for outputs,
and actually run it!

Cheers!
Rich
 
W

Winfield Hill

Jan 1, 1970
0
Rich, Under the Affluence wrote...
4 x 4 hardware multipllier!

OK, it ain't much, and I have no idea if it will work, except watching
the bits all follow their little truth tables in my mental simulator ...
I drew this in Xiilinx, but have no idea yet how to run a simulation,
or dump it to the bitstream that could program the chip (BTW, did I
say that a prospective client has sent me a "CPLD 95XL DEMO BOARD"?
He sent it to me in case I got this one gig, which I think that by
chatting him up on the telephone, I inspired him to find a better,
cheaper faster way, and so talked myself out of a job, but as a sort
of gratituity, I think he's going to let me keep the board. And the
Software. :)

Nope, the job is still sitting there, like an unscratched itch.
I just haven't written up the spec and fired off the P.O. yet.
:>)
 
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